Bought one of the XFI cams for factory roller lifters. Installed it and degreed it. Started on #1 cylinder, all points at .006 were good except for the intake closing. It was 5 degrees off. Made what should have been a 268 duration 273 degress. For this cylinder it turns the 113 LSA into 114.25 and the ICA goes from 109 to 111.5. So I checked the #3 intake duration. 272. The #5 intake, 277!

Called Comp tech. Checked my serial number and told me they measured 272.7 on the #1 intake and they don't measure others. So I asked how much out is allowed. 4 DEGREES EACH WAY @.020, 8 TOTAL!! So, for my 268 intakes, 264-/272+ @.006 is acceptable. and for the 276 exhaust, 272-/280+. Think of all the possible cam points on one camshaft. One cylinder could be 264/280 and another 272/272. Same goes for all the LSA possibilities.

I am returning it and now I find they don't reimburse shipping because they pay for the shipping on the second one to me. So, you buy and pay shipping. Then you find they screw up and you pay to ship their screw up back to them and they don't send a new one out unless you return the bad one.

Also, that 4 degrees is for CNC items that are the generic cams. Custom cams are sent out with closer tolerances and are done by hand. Same price though. I told them get me a good one no matter how it is made and include the measurements for all 16 lobes. Damn expensive cam for this kind of crap.

I have trusted this outfit more than others out there but that is changing here fast.

 

Did you actually measure the centerlines to come up with these figures, or are you just guessing based on your .006 numbers? I wouldn't be too concerned with slight variations at the tail ends of the ramps.

 

I'm with Aperion on this. The measurements at .050" are far more important than .006". But it is not unusual for "off-the shelf" cams to be out a +/- a couple of degrees at .050.

 

i have heard of issues like this from the big grind makers and have always stayed away from them personally.

try Larry at Laser cams

he is a wealth of knowledge and they make their own cams
it either lasercams or lazercams.com

like its said, you get what you pay for , no matter where you buy

 

That is why I use Isky mostly. I don't trust comp cams. This is the same company that used to be called competition cams but they got a bad name so they shortened the name and started advertising heavily and sponsered almost anyone to become the most recognised name in cams. One of the first cams I helped a buddy install was a competition cams back in like 1989. Installed straight up it was way off on the degree wheel. The car afterwards loped more and ran rougher but it gained only .3 in the quarter. In three months it began to run horribly and after inspection one lobe on the camshaft was completely gone and 2 more were worn down. I found out that comp cams heat treats their cams in batch and they will have hundreds of cams stacked on top of each other during this process. It's little wonder that their hydralic cams have lobe hardness issues. I have heard other storys from other people that are very similar. We installed a isky mega cam and installed straight up it was dead on and the car gained .9 over the previous best with the comp cams. Other experiences may vary and you may not have any troule with a hyd roller cam but I won't use them again that's for sure. Prob stirred a hornets nest here so let'er rip I guess. LOL

 

Get what you pay for? Comp will charge you $363.67. I think Summit is about $280.


Yes, I came up with the angle by just going off the points. I can see there being irregularities on the surface and LSA not being affected, but that would be a lot of waviness on the surface and I couldn't see that the other numbers are not affected.

So, I went ahead and got the ICA and ECA from measuring, they don't match at all. Not only must there be irregularities at the low lift points but the top of the lobes as well as the highest point does not correspond as it should. My guess was .050 would be not better, so...

Went ahead and checked with Comp to see on other points and this is what they would tell me on my #1 intake lobe: 4 degrees off @.020 and 3 degrees @.050. Not the actual durations and no 4.this and 3.that like I got with the 272.7 @.006 from them.

Here are the specs,
1st the cam card numbers:
25 63
75 21

113 LSA
109 ICA
117 is what the ECA comes out to



Actual as I measured:
25 68
75 21

108 ICA
114 ECA

111 is what the LSA comes out to if these were actually the centers.


Like I said, I get goofy duration numbers on the other intakes I measured and I imagine the other figures would be just as random. Now, why is it so stressed that the cam be degreed if this is acceptable? Why would you do it if you can't tell what is going on anyway?

 

I have the exact same cam sitting in my garage waiting to go into my rebuild. My cam card says the same as yours. I will have to wait for Dyno Don to install mine to get the real numbers.

A friend had a Lunati cam that was off 7 degrees from straight up. So yes it does pay to degree the cam. You would think with all the modern equipment they could hold closer tolerances.

 

Like I mentioned earlier, I was told they get more accurate results by doing the cams by hand over CNC. When I was in my drafting course about 10 years ago, one of the classes in the program had us visit an engineering program at the university and a metal parts fabricating business. We took a fair amount of time going over CNC manufacturing and I was never under the impression that a human being could perform nearly as well as the CNC process.

 

I went through 2 comp camshafts with lobe hardness issues. one was just about wiped after 5000miles the one i replaced it with lasted 100 miles and took my engine with it. these two were manufactured 2 years apart. I was told that its normal for them to be a few degrees off and the both were only 2 or 3 deg off on the wheel

 

Are you reading the dial indicator off the edge of the lifter or from the lifter plunger center or pushrod?
Ahydraulic lifter's plunger will compress some as you turn the motor over creating errors. The dial indicator must be straight over the lifter so the dial indicators punger is perpendicular to the lifter bore or geometric errors will result.

You realize that modern cams have nonsimetrical lobes.
meaning the opening ramp and flank is not the same as the
closing side, therefore you cannot determine the lobe C/L
or max lift point from the .006" lifter lift points or even the .050" lift points. You should measure the Lobe centerline by measureing .100" down from max lift on each side of the lobe's max lift point. It is very likely different then the calculated center of the .050" points or the .006" points.

At any rate the cam's timing points should be within 1 degree of the design numbers and consistant on all lobes or it's junk. Not 3 or 4.

What ever happened to quality control?

A CNC cam grinder is only as good as the guy who sets it up and maintains it.

I could see this from a $69 generic cam but not from the supposed "Leader" in the racing cam/ valvetrain industry.

Try Isky, Crane or Engle Cams among others. All these guys were grinding cams long before Comp Cams came along.

I'll bet the $69 generic Cams by "On sale" are more accurate than 4 degrees +/-

 

Took it off of the lifter edge. Heads not installed yet.

If I couldn't get my results to repeat, it would obviously be my issue, but I got the same numbers over and over. 277 on a 268 speced lobe! Junk!

Good point about non-symetrical lobes, forgot about that. My mind was not into cam design at the time I started taking the measurements. Was more concerned about the whole engine assembly process I am working on rather than the theory of just one element.

 

I just put in the 292XFI cam in my '89.....I like it alot. Sounds killer and untuned it put 347hp to the wheels on a Mustang Dyno....and thats with the exhaust choking it off at 5700 rpm's....I've had good luck with thier tech guys....


my .02 350Z

 

Update

After waiting a week and much lying BS from their tech and warranty guys, someone there stepped up. After he checked into my cam situation, they found their problem and overnighted a new one to me. I have a couple of engines full of Comp parts and that was about to all change in the future for me. I do wonder about some other parts I have but it is nothing I am worring about right now.

 

so the new cam spec'd out ok? i was thinking of running a xfi cam in my car and now i read this and got a bit disspointed..

 

The replacement is good enough for me.

If I was to do it again and knowing what I now know, I would get the complete specs (camshaft certification) from the maker for the cam I am going to receive. This is with any manufacturer. If one can't do that for me in the future, they are not serious enough about their business and I find someone who will and buy from them. There would be now good reason why someone can't verify their work, especially on a part like this.

 

wow this suprises me, i havent dealt with comp in a year or so but my dad has been using custom grounds for his race cars for a LONG time, we have never had a issue with them.